Engine starting mechanism



May 26, E942,

H. E. BAER l ENGINE lSTARTING AMECHANISM l'Film1'Fehn', 1941 2Sheets-sheet 1 May 26, 1942. H. E. BAER 2,284,358

` ENGINE STARTING MECHANISM 'Filed Feb. 7,.l941 2 Sheets-Sheeil 2 r e mwN/ WVU md .m Y mw, m f l ma v WMV/4272,33 uw a mm, i, YW Q, a mmm.. m.wm l n I; Il I mm. l mm, MN mv mm R, mm mlll mm www m M mw a, I Y&W/////////,/

Patented May 26, 1942 ENGINE STARTING Howard E. Baer, Garnele, N. J.,assignor to BendixY Aviation Corporation, South Bend, Ind., a.corporation of Delaware Application February 7, 1941, serial No. 377,900

s claims. ici. 121-37) This invention relates to engine starters adaptedfor utilizing uid pressure, as from air precompressed into a reservoiror from anvexplosive cartridge, the fluid pressure being Operable upon aconfined piston in the illustrated embodiment of the invention.

One of the objects of this invention is to provide a novel method of andmeans for protecting the starter parts from the adverse effects thatmight otherwise be produced by a back-fire, or premature ignition of theengine to be started.

Another object of the invention is to provide a novel valve mechanismand other improvements in the type of engine starter disclosed in PatentNo. 2,144,196 granted by the United States Patent Oilice on January 17,1939, the nature and Vscope of which improvements are indicated in theaccompanying drawings and the following particular description of oneform of mechanism embodying the invention. It is to be understood,however, that the drawings are for the purpose of illustration only, andare not designed as a definition of the limits of the invention,reference being had to the appended claims for this purpose.

In the drawings, v

Fig. 1 is a longitudinal sectional View of a device embodying' theinvention;

Fig. 2 is a transverse sectional view on line 2-2 of Fig. 1;

Fig. 3 is an exploded perspective view of the novel valve and controlmeans therefor;

Fig. 4 is a view similar to Fig. 2, but showing the valve in its otherposition; and

Figs. 5, 6 and 7 show the valve control means in three positionssuccessively assumed.

Where the engine starter is ofthe type having a clutch element shiftablealong, and rotatable about, the axis of an engine member to be engagedthereby, the housing of the starter will include a part I9 having acircumferential flange II for registry with and supported on a mountingange |2 of the engine crank-case, preferably with the aid of bolts I3.Part I also includes a threaded shank I4 to receive cylinder IB whoseinner surface is engaged by the packing rlngs I1 and skirt |B of thepiston |9 constitut.

ing the part to be moved, and whose outer surface includes a threadedportion 2| to receive the head end 22 of the motor. Integrated with thepiston I9 is a long tube 23 which coacts with the assembly (to bedescribed) governing exhaust of pressure uid from the cylinder IB.Admission of pressure uid is by Way of the tube 26 (Fig. 2) leading froma pressure source and intruding into chamber 21 of the head 22, fromwhich chamber the fluid passes into working chamber 28 to act upon thepiston I9; there being a constantly open passage directly connectingcham bers 21 and 28.

Rectilinear travel of piston I9, induced by the pressure of the fluidadmitted to chamber 28, causes rotation of the engine-engaging clutchelement 29, the translation from rectilinear to rotative movement beingbrought about Vthrough the agency of the inter-engaging screw threads onsleeves 18 and 3| (Fig. 1), the former being advanced longitudinally bythe advance of the piston, and the rotation of the sleeve 3| beingcommunicated to the clutch element 29 due to the splined connection 32therebetween. Springpressed balls 33 transmit vthrust to sleeve 3|,spring 39 and clutch 29 to shift the latter into engagement with enginemember 39, to be driven. Following such engagement, which is facilitatedby the friction of sealing ring 36 exerted on the outer cylindricalsurface of clutch 29, the balls 33 are pressed toward each other by thetelescoping action of tube 23 within sleeve 3|, caused by the continuingadvance of piston I9.

The subsequent exhaust of the fluid from chamber 28 takes place througha valve mechanisrn of novel construction, and including a rotary head 31having a number of equally spaced ports 38 adapted to register with anequal number of ports 39 cut through the partition 6| which separatesthe working chamber 28 from the exhaust chamber 92, feeding exhaustconduit 43; the latter being retained in threaded socket 22a of head 22by suitable retaining means 25. During admission of fluid to the workingchamber 28 (by way of inlet conduit 2S and inlet chamber 21) the valvehead 31 is yieldably held (as by spring-pressed detentl) in the positionindicated in Fig. 2, in which position the ports 38 are out of registrywith ports 39 and therefore no fluid can escape to the exhaust chamber42. Registry between ports 38 and 39 is subsequently effected, 'topermit fluid discharge, by reason of the following valveactuatingelements: The tube 23 (heretofore described) is internallysplined, at 41 and 58 (see Fig. 3) to receive the splines 5I and 52,respectively, formed on the periphery of ascrew-nut 53, and slides upona screw rod 51 having threads 58 at its rear end, for attachment to thethreaded bore of valve head 31, and additional threads 59 near itsvfront end, for coaction with the mating threads cut internally ofscrew-nut 53. Upon 'admission of uid under pressure, said fluid acts toadvance piston I9, and

also acts upon member 3, tending to move the latter forward and thusrotate valve rod 51 and valve head 31; but the adjustment of the springpressure on detent 48 is such that the restraining influence of saiddetent is just sufiicient to resist such turning tendency during normalduid pressure conditions. When the advance of piston I3 brings thepiston-carried collar 58 into engagement with the splines 5I and 52 ofscrew-nut 53,

further advance causes corresponding axial movement of said screw-nut,as shown in Fig. 5. Such axial movement of the screw-nut 53 (rotationbeing prevented by splines 41, 48) produces a motion translation, byreason of threads 59, resulting in rotation of screw-rod 51. At thistime the detent 46 necessarily yields; its resistance being no longersunlcient to prevent rotation of rod 51. This rotation of screw-rod 51carries the valve head 31 from the angular setting shown in Fig. 2, to anew angular setting as shown in Fig. 4, thereby effecting registrybetween ports 38 and 39, and opening a path for exhaust of the operatingfluid from thev working chamber 28. During this exhaust action detent 6lyieldably holds the valve, and the shoulder 62 in head 22 positivelyprevents over-travel of the valve in one direction, as does shoulder 63in the opposite direction; both being in the path of valve tail 64.

The return stroke of piston I9 (induced by spring 14 acting throughparts 1B, 11 and 18) occurs while exhaust valve 31 remains in the openposition (Fig. 4); but near the end of said return stroke there is are-engagement of splines 5| and 52 with the shoulders 65 of splines 41and `48 (as indicated in Fig. 6) whereupon thenal stage of returnmovement draws screw-nut 53 to the right, as viewed in Fig. 6, andproduces a screw action upon screw-rod 51 which rotates said screw-rod(and valve 31, integrated therewith) in a clockwise direction, as viewedin Fig. 4, therebyy returning the valve 31 to the closed position, asshown in Fig. 2; all uid having by this time been discharged. The partsthen come to rest in the original position (Fig. 1).

, The cycle above described is the normal one by which the engine issuccessfully cranked. There are occasions, however, when the cranking isinterrupted by a premature ignition in one or more cylinders, causingthe engine crankshaft to rock in the reverse direction and therebyproducing a corresponding reverse rotation of the engine-engaging member29, and of the starterdriven screw 3l to which said member 29 issplined, as shown at 32. Such reverse rotation will stop the forwardmovement of the driving screw 18, but as the fluid supplied throughconduit 21 will continue to enter the chamber 28, it will steadilyincrease the pressure therein.

Now as this pressure acts not only upon the piston I9, but also upon theright-hand end surface of valve controlling member 53the uid havingaccess thereto by reason of the clearance between collar 56 and sleeve51, as shown best in Fig. 3-the increased pressure thus created uponsaid right-handsurface will be effective to overcome the restrainingeffect ci yieldable detent 46, and move member 53 to the left, thusproducing motion translation to rotate rod 51 in the same manner as itis normally rotated by the engagement of collar 55 with member 53, asabove described. Such rotation of rod 51 will open valve 31 and thus theaccumulative fiuid will be vented to exhaust, thereby preventing anexcessive pressure build-up to a dangerous point. Following thispressure release, spring 14 will return the pistoni! in the usualmanner, thus re-closing valve 31 and conditioning the starter for a newcranking stroke; the reverse rotational impulse of the engine under the"backfire having in the meantime expended a major portion of itsreverselyl acting force, so that it will be comparatively easy for thestarter to resume cranking.

What is claimed is:

1. In an engine starter, in combination, a cylinder and piston, saidcylinder constituting a iluid receiving chamber in which said pistonmoves when subjected to fluid pressure, inlet and exhaust chambers atone end of said cylinder, said inlet chamber having constantcommunication with said fluid receiving chamber, rotary valve meansnormally preventing communication between said fluid receiving chamberand said exhaust chamber, and valve opening means responsive to fluidpressure of abnormal magnitude to rotate said valve means to a positionestablishing communication between said uid receiving chamber and saidexhaust chamber.

2. In an engine starter, in combination, a cylinder and piston, saidcylinder constituting a fluid receiving chamber in which said pistonmoves when subjected to iluid pressure, inlet and exhaust chambers atone end of said cylinder, said inlet chamber having constantcommunication with said iiuid receiving chamber, rotary valve meansnormally preventing communication between said uid receiving chamber andsaid exhaust chamber, valve opening means to rotate said valve means toa position establishing communication between said uid receiving chamberand said exhaust chamber, and piston-carried means engageable with saidvalve opening means to cause the latter to open said valve means whenthe piston reaches a predetermined position in its movement in saidcylinder.

3. In an engine starter, in combination, a cylinder and piston, saidcylinder constituting a uid receiving chamber in which said piston moveswhen subjected to fluid pressure, inlet and exhaust chambers at one endof said cylinder, said inlet chamber having constant communication withsaid fluid receiving chamber, rotary valve means normally preventingcommunication between said fluid receiving chamber and said exhaustchamber, valve opening means responsive to fluid pressure of abnormalmagnitude to rotate said valve means to a position establishingcommunication between said uid receiving chamber and said exhaustchamber, and piston-carried means engageable with said valve openingmeans to cause the latter to open said valve means when the pistonreaches a predetermined position in its movement in said cylinder,independently of the degree of uid pressure then existing.

4. In an engine starter, in combination, a cylinder and piston, saidcylinder constituting a iluid receiving chamber in which said pistonmoves when subjected to fluid pressure, inlet and exhaust chambers atone end of said cylinder, said inlet chamber having constantcommunication with said iiuid receiving chamber, valve means normallypreventing communication between said iluid receiving chamber and saidexhaust chamber, valve opening means responsive to uid pressure ofabnormal magnitude to\shift said valve means to a position establishingcommunication between said iluid receiving chamber and said exhaustchamber, and piston-carried means engageable with said valve openingmeans to cause the latter to open said valve means when the pistonreaches a predetermined position in its movement in said cylinder,independently of the degree of fluid pressure then existing.

5. In an engine starter, in combination, a cylinder and piston, saidcylinder constituting a fluid receiving chamber in which said pistonmoves when subjected to fluid pressure, inlet and exhaust chambers atone end of said cylinder, said inlet chamber having constantcommunication with said iiuid receiving chamber, valve means normallypreventing communication between said fluid receiving chamber and saidexhaust chamber, valve opening means responsive to fluid pressure ofabnormal magnitude to shift said valve means to a position establishingcommunication between said uid receiving chamber and said exhaustchamber, piston-carried means engageable with said valve opening meansto cause the latter to open said valve means when the piston reaches apredetermined position in its movement in said cylinder, independentlyof the degree of fluid pressure then existing, andA means for returningsaid piston to its initial position in said cylinder, saidpiston-carried means being operative, during such return movement,

to reclose said valve means.

6. In an engine starter, in combination, a cylinder and piston, saidcylinder constituting a.

fluid receiving chamber in which said piston moves when subjected tofluid pressure, inlet and exhaust chambers for said cylinder, said inletchamber having constant communication with said fluid receiving chamber,valve means normally preventing communication between said fluidreceiving chamber and said exhaust chamber, to shift said valve means toa position establishing communication between said iiuid receivingchamber and said exhaust chamber, reciprocable means engageable withsaid valve shifting means to cause the latter to open said valve meanswhen the piston reaches a predetermined position in its movement in saidcylinder, independently of the degree of fluid pressurethen existing,and means for returning said piston to its initial position in saidcylinder, said reciprocable means being operative, during such returnmovement, to re-close said valve means.

HOWARDl E. BAER.

